Field
The present disclosure relates to optical communication equipment and, more specifically but not exclusively, to sub-wavelength granularity for transport of multicarrier optical signals, e.g., optical orthogonal frequency-division multiplexed (OFDM) signals.
Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Orthogonal frequency-division multiplexing (OFDM) is a multicarrier transmission technique in which data are transmitted using a plurality of mutually orthogonal subcarriers. In optical transport systems, OFDM has received increased attention as a means to overcome certain shortcomings of single-carrier and/or wavelength-division-multiplexing (WDM) optical transport systems. For example, coherent optical OFDM (CO-OFDM) is viewed as beneficially combining the important advantages of both coherent detection and OFDM modulation. In a conventional physical-layer implementation of CO-OFDM, the transmitter up-shifts the baseband OFDM signal to optical frequencies using an optical I/Q modulator that modulates a carrier wavelength generated by the transmitter's laser, and the receiver downshifts the corresponding received optical OFDM signal to baseband using the receiver's optical local oscillator. Conventional CO-OFDM transport is typically implemented with undivided wavelength granularity, according to which all OFDM subcarriers corresponding to the carrier wavelength are handled together.